Is there a specific thread or article or vid you'd recommend to cut through nonsense to make smart decisions on that topic? On a search, this was the thread that came up for me. Might be a topic for Gene at al to cover in a vid. If he did, I didn't find it.
Spikes couple to the floorboard. Rubber feet would more likely decouple. (Carpet is considered to decouple.)
Is there an audible advantage? Likely not.
The probable exception to the rule is subwoofers and suspended wood flooring, especially if the wood floor is spongy or bouncy.
At the end of the day this is largely about the transference of physical energy from room to equipment or equipment to room.
Perhaps a better way to describe the latter is the desire of some/many to isolate an amplifier. In a room full of audio equipment, including the speakers which will be creating energetic wavefronts,
some (not I) will argue (I've seen it) that you want a combination of coupling the amplifier to the room for stability and decoupling it from the stand so that it can absorb and diminish any airborne vibration... the best example I've seen is a sand filled box on spikes with isolation between the box and the amp.
Does this matter in real life? Couldn't tell ya: Just reporting.
Spikes on speaker stands are about stability. You want to couple to the floor board through carpet. Example: I have 32# speakers on 36" stands on a medium-pile carpet. If I used the rubber feet, the stand would not be stable. With spikes punched through to the floor board and successfully leveled, that heavy speaker on a tall sand-filled stand now has secure footing (and a lower center of gravity due to the sand in the tubes). It is stable enough that an accidental bump will not topple it.
Does the sand affect sound transmission? Couldn't tell you. Many say the steel won't ring no matter what. A few say it will. I just know that the physics involved in the stability of the stand indicated lowering the center of gravity.
Yes, when I tap those filled tubes with a screwdriver or such tool, they thud now instead of ring, but that really assumes that there would be enough transference of energy from a presumably well designed/built/damped speaker cabinet to excite the dense steel tubing into ringing... *shrugs
To wrap my interest in this... I have very spongy suspended wood flooring. For my Subs and Mains, I discussed the concern about room vibrations as I had witnessed my room jiggling when I walk across it. My solution was aggregate filled concrete pads (which are pretty acoustically dead (Granite Slabs are best and Maple very good)) from a custom concrete shop's scrap yard (rejected countertops). I mounted these on outriggers with adjustable spikes, and put isolation feet between the cabinet and the pad.
Prior to this, my Subs would vibrate the room. Sympathetic vibrations everywhere. Just putting them on the pads alone, on the carpet, did not significantly change anything: still a significant amount of vibration passed through to the structure. Installing the spikes and isolation feet did truly cut back on the transference of physical energy. Most vibrations ceased. This does not stop true acoustical vibration from occurring, and in some music and movies, I will still experience rattles. If I had to quantify how effective this is, I would say about 85%.
Does my Bass sound any different? No: this does not change how the Transducer in the cabinet performs its job.
And yes, it has changed the way the Transducer-Cabinet system interacts with the room/structure, so while the Transducers performance is not changed, the interaction with the room is.
The sad part is that while I agree with TLS, there is some truth behind the Audiophool myth that needs to be separated.
Coupling and Decoupling isn't going to change your sound. It's not going to give you that 1% or .01% improvement in performance. It may help you more safely install a speaker stand... Or as I described, it may help reduce some physical transference of energy from cabinet to structure.
If you really buy into the possibility that the vibration caused by a soundwave might disrupt your amplifier, then go for it. Build a stand and buy some spikes and isolation feet and have fun. If you find a way to measure the result, cool. Please share.
But for the rest of it, it is largely a solution in need of a problem. The problem can exist, but is much more rare that the majority of Dealers would have you believe, I think.